samba - Mar 2003 - Create Mode set to 775 but files created at 764

My office is running Windows NT 4.0 workstations and a Sun Solaris
server. My friend and I are trying to get Samba to work on our Solaris
servers.  The Samba installation seems to go fine. We created our share and
set create mask to 775. But every time we create a file the permissions get
set to 764.  We tried using force create mask and it works.  However we want
our employees to be able to set their files to read only if they choose too.
With force create mask this is impossible, because it won't allow the
permissions to be set to anything but 775. I thought  that maybe we had
messed up something on the server, so I tried it on a couple of Linux
servers I had... same problem. The funny thing is that directory mask is
working properly, but create mask is not.